Super Powered Water: Cohesion and Adhesion

Confession time. When I was a kid, I was pretty sure I had some latent superpower that had yet to manifest itself. I knew that if I waited long enough, something would happen to trigger these hidden abilities and I would be off on a lifelong mission to fight crime and save innocent lives from destruction. Then, after a lot of patient waiting, something happened that I thought was going to be the key to my life of superhuman adventure.

I was taking a shower and I noticed that the water would run down my arm, fly off my outstretched fingers, and shoot through the air. Surely this was it! All that was needed was to develop my powers further through training and dedication. Was I going to be Water Boy? Aquaman? Maybe I would be able to freeze water too, like Iceman. Unfortunately it wasn’t long before I discovered that not only was my superpower not getting any more super, but it turned out that I wasn’t the only one this happened to.

Sadly it turned out that this superpower didn’t belong to me at all. It was just one of water’s many extraordinary abilities. Before we explore some of water’s many amazing talents, let’s take a look at the source of it’s powers.

Hydrogen Bonds

Water doesn’t derive its many abilities from exposure to cosmic rays, a radioactive spider bite, or from a rare genetic mutation. The secret to water’s greatness lies in its ability to form hydrogen bonds.

In a previous episode on atomic bonds, I mentioned that water molecules are formed when one oxygen atom forms covalent bonds with two hydrogen atoms. The oxygen atom shares one electron with each hydrogen atom, which in turn share one electron each with oxygen.

We also mentioned that since oxygen is more electronegative than hydrogen, the pair of shared electrons tend to spend more time hanging around the oxygen side of the water molecule than they do around the hydrogen side. Since the electrons spend so much more time around oxygen, it gets a sort of partial negative charge. Likewise, since hydrogen spends so much extra time without the shared electrons, it has a partial positive charge.

As you might have heard, “opposites attract.” While this may or may not be true in the world of romance, it is definitely true in the world of chemistry. When two water molecules drift by each other, the partial positive charge of a hydrogen atom on one molecule pulls it towards the partial negative charge of the oxygen atom on the other molecule. These tenuous relationships are called polar bonds or hydrogen bonds and it turns out that these bonds are the source of water’s amazing powers.